A currently existing thermosensitive recording medium or material is used in combination with a heat transfer sheet having a heat transfer layer containing thermally transferable dyes. That material is superposed upon the heat transfer sheet while said heat transfer layer is in contact with an image receiving or imageable layer. Then, heat is applied by such thermal printing means such as a thermal head which is controlled by an electrical signal corresponding to image information from the back side of the heat transfer sheet with a thermosensitive printer, etc. to generate heat, thereby transferring the dyes in the heat transfer sheet into the image receiving layer to form a gradient image like a natural color photograph. Typical of this is a thermosensitive image-receiving sheet.
Such a thermosensitive recording material has a disadvantage of making it difficult to provide a satisfactory releasing of the heat transfer sheet from the recording material, because the heat transfer layer (a dye layer) is thermally fused to the image-receiving layer (a dye-receiving layer) by heating at the time of printing with a thermal printer. To eliminate this disadvantage, it has heretofore been proposed to incorporate a release agent in a resin for forming the dye-receiving layer by mixing.
With the dye-receiving layer in which the release agent is only mixed with that resin, however, the heat resistance of the dye-receiving layer per se is less than satisfactory with no achievement of sufficient releasability, partly because the release agent remains only mixed with said resin.